This invention relates generally to utility and hygienic paper towels and, more specifically, to the use of special emulsions as impregnating and softening compositions.
The generic term “paper” encompasses about 3000 different types and articles which can differ, sometimes considerably, in their applications and their properties. Their production involves the use of numerous additives among the most important of which are fillers (for example chalk or kaolin) and binders (for example starch). For tissues and hygienic papers, which come into relatively close contact with the human skin, there is a particular need for an agreeable soft feel which is normally given to the paper by careful selection of the fibers and, in particular, by a high percentage of fresh mechanical wood pulp or cellulose. However, in the interests of economic paper manufacture and from the ecological viewpoint, it is desirable to use large amounts of inferior-quality deinked wastepaper. Unfortunately, this means that the softness of the paper is significantly reduced which is troublesome in practice and can even lead to irritation of the skin, particularly with frequent use.
Accordingly, there has been no shortage of attempts in the past to treat tissue papers by impregnation, coating or other surface treatments in such a way that a more agreeable soft feel is achieved. International patent application WO 95/35411 (Procter & Gamble) relates to tissue papers coated with softening compositions which contain 20 to 80% by weight of a water-free emulsifier (mineral oils, fatty acid esters, fatty alcohol ethoxylates, fatty acid ethoxylates, fatty alcohols and mixtures thereof), 5 to 95% by weight of a carrier (fatty alcohols, fatty acids or fatty alcohol ethoxylates containing 12 to 22 carbon atoms in the fatty group) and 1 to 50% by weight of surfactants with an HLB value of preferably 4 to 20. The Examples mentioned in this document all contain petrolatum as emulsifier. International patent application WO 95/35412 discloses similar tissue papers where water-free mixtures of (a) mineral oils, (b) fatty alcohols or fatty acids and (c) fatty alcohol ethoxylates are used as softeners. International patent application WO 95/16824 (Procter & Gamble) describes softening compositions for tissue papers containing mineral oil, fatty alcohol ethoxylates and nonionic surfactants (sorbitan esters, glucamides). In addition, International patent application WO 97/30216 (Kaysersberg) describes softening compositions for paper handkerchiefs which contain (a) 35 to 90% by weight of long-chain fatty alcohols, (b) 1 to 50% by weight of wax esters containing 24 to 48 carbon atoms, (c) 0 to 20% by weight of nonionic emulsifiers and (d) 0 to 50% by weight of mineral oil. From the applicational standpoint, however, the softness and feel of the treated papers are still in need of improvement.
Accordingly, the problem addressed by the present invention was to provide compositions with which dry utility papers, more particularly tissue papers, and tissue cloths having a particularly agreeable soft feel and excellent skin-care properties could even be produced using raw materials comprising a high percentage of recycled paper. At the same time, only readily biodegradable auxiliaries would be used and the compositions would penetrate easily into the tissue, would be uniformly dispersed therein and, even in highly concentrated form, would have such a low viscosity that they would be easy to process.